I am getting the error message: dpkg: unrecoverable fatal error, aborting:
files list file for package 'nautilus-sendto-empathy' is missing final newline
E: Sub-process /usr/bin/dpkg returned an error code (2), when I try to upgrade, or download software. Since I upgraded from 12.04 to 12.10, I have continually received system error messages on-screen when I log in, though this is after I go on Firefox, and it may be a Firefox error. But I am unable to update any software ever since the upgrade. I have fiddled about a bit, and unticked some items in the software system settings. Now the error message I get is the one you see above.
Would it be better if I reinstalled my good old 12.04? I am not very good with technology and need to be 'led'.
Thanks for your thoughts.

The error message indicates that file /var/lib/dpkg/info/nautilus-sendto-empathy.list is corrupt (missing final newline). This is how the file should look like. Besides the files listed on the linked page, it also should contains folders they are in and all directories above those in the path, i.e. /usr/share/doc, /usr/share, /usr, /usr/lib, /usr/lib/nautilus-sendto, etc. Compare this with what in the file on your system.

Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
libhal1
The following NEW packages will be installed
libhal1
The following packages will be upgraded:
adobeair
1 upgraded, 1 newly installed, 0 to remove and 338 not upgraded.
Need to get 0 B/16.2 MB of archives.
After this operation, 239 kB of additional disk space will be used.
Do you want to continue [Y/n]? y
Selecting previously unselected package libhal1.
dpkg: unrecoverable fatal error, aborting:
files list file for package 'nautilus-sendto-empathy' is missing final newline
E: Sub-process /usr/bin/dpkg returned an error code (2)